Does evidence support raw food diets?

Feeding a complete or primarily raw food diet is an increasingly popular option being taken up by pet owners, but analyses of the evidence corroborate the reality that research is severely lacking. Feeding cats and dogs on raw diets should be approached with caution until adequate evidence is garnered, conclude two reports in Veterinary Evidence.

“The majority of scientific research on these diets focuses on food safety and zoonosis risks, whereas the effects of raw food diets on animal health remain mostly unknown,” said Nieky van Veggel, a companion animal health and nutrition expert and Senior Lecturer in Bioveterinary Science at Writtle University College.

“Vets and vet nurses should ensure owners are aware of the risks involved in feeding raw food diets so that owners can make an informed decision.”

The evidence (or lack of)

Much of the research into this area has focused on the risk factors for infectious disease – in humans and animals – associated with the possible existence of pathogens, particularly in raw meat, and subsequent contamination of the environment surrounding a pet and its owner.

As a result, there is a gaping hole in the evidence, and the wider health and nutritional benefits or risks of raw food diets remain relatively unknown. This has been demonstrated by two Knowledge Summaries in Veterinary Evidence.

In April 2018, a search of the available veterinary literature was conducted in an attempt to answer whether raw food increases the risk of kidney stones in dogs compared to feeding a dry kibble diet. The evidence in the report – entitled: “In adult dogs, does feeding a raw food diet increase the risk of urinary calculi formation compared to feeding a complete dry kibble diet?” – amounted to just one study that provided weak evidence that neither supported nor challenged the hypothesis.

Even more striking was the outcome of a literature search in 2017 targeted towards finding out whether a raw food diet was more effective than kibble at reducing periodontal disease – not a single piece of relevant research was identified. The authors of that Knowledge Summary – “In dogs with periodontal disease is feeding a complete raw meat diet more effective than a complete kibble ‘dental’ diet

at reducing periodontal disease?” – highlighted this discovery as “representative of the lack of research on raw feeds and feeding”.

These examples are not exceptions. A 2011 article in The Canadian Veterinary Journal, entitled “Raw food diets in companion animals: A critical review”, stated that, at the time of its publication, not one study looking at the nutritional risks or benefits of raw meat feeding in dogs and cats existed in the top three levels of evidence. The only published information was of poor quality or not reliable.

As a result, and since the majority of current recommendations for the adoption of raw food diets come from anecdotal sources, Nieky said: “Vets should advise owners interested in raw food diets to follow strict food hygiene guidelines, and use their clinical experience to determine whether a raw food diet is right for individual patients.”

Jennifer Parker, BSc, PgDip, MSc, is a science writer and editor. She studied zoology, endangered species re-covery and palaeoanthropology in the UK. Jennifer was Senior Editor of Veterinary Practice magazine for almost three years; she left the publication in October 2019 to move abroad and pursue a freelance writing career.